UNDERSTANDING THE SOURCES AND SUBSEQUENT EVOLUTION OF PLASMA WITHIN A PLANETARY MAGNETOSPHERE HOLDS INTRINSIC IMPORTANCE FOR MAGNETOSPHERIC DYNAMICS. FOR EXAMPLE THE BALANCE OF ENDOGENIC AND SOLAR WIND PLASMA CAN BE USED TO STUDY THE RELATIVE IMPORTANCE OF DIFFERENT SOLAR WIND-MAGNETOSPHERE INTERACTIONS AS A SOURCE OF MAGNETOSPHERIC PLASMA. RECENT STUDIES USING OBSERVATIONS FROM THE CHARGE-ENERGY-MASS SPECTROMETER (CHEMS) ONBOARD CASSINI HAVE REPORTED SEVERAL ASYMMETRIES IN THE MISSION-AVERAGED ABUNDANCE OF SOLAR WIND-ORIGINATING HE++. FURTHER STUDY IS NEEDED TO BETTER UNDERSTAND AND DETERMINE WHICH PROCESSES LEAD TO THIS SPATIAL DISTRIBUTION. ONE POSSIBLE PROCESS FOR SOLAR WIND PLASMA ENTRY INTO A MAGNETOSPHERE IS THROUGH DUNGEY-CYCLE MAGNETIC RECONNECTION. DUNGEY RECONNECTION HAS BEEN SHOWN TO ALLOW FOR SOLAR WIND ENTRY AT THE DAYSIDE MAGNETOPAUSE THROUGH SUB-SOLAR RECONNECTION AS WELL AS IN THE MAGNETOTAIL VIA THE RECONNECTION OF LOBE FIELD LINES. AT SATURN THE DUNGEY-CYCLE MAGNETOTAIL RECONNECTION SITE IS KNOWN TO HAVE A DAWN-WARD BIAS WHICH MAY CONTRIBUTE TO THE OBSERVED DAWN-DUSK ASYMMETRY. ANOTHER PROCESS FOR SOLAR WIND ENTRY IS ASSOCIATED WITH KELVIN-HELMHOLTZ INSTABILITIES (KHI). AS THE KHI VORTICES EVOLVE MAGNETIC RECONNECTION CAN OCCUR WITHIN THE STRUCTURES RESULTING IN THE FORMATION OF A MIXING REGION. THIS PROCESS HAS BEEN OBSERVED AT EARTH IN RECENT YEARS. HOWEVER FOR FAST ROTATORS SUCH AS SATURN THE SPEEDS AT WHICH THE KHI VORTICES MOVE ALONG THE FLANK MAGNETOPAUSE ARE DIFFERENT FOR THE DAWN AND DUSK FLANK. WHILE A DAWN FLANK KHI VORTEX WILL MOVE SLOWLY TOWARD NOON THE MORE NUMEROUS DUSK FLANK KHI VORTICES QUICKLY MOVE DOWN-TAIL. JUST HOW THE DAWN-DUSK DIFFERENCES IN PROPAGATION SPEEDS AND OCCURRENCE RATES OF KHI VORTICES WILL AFFECT THE ACCESS OF SOLAR WIND IONS INTO THE MAGNETOSPHERE IS CURRENTLY UNKNOWN. SINCE THIS DAWN-WARD BIAS FOR SOLAR WIND ENTRY COULD BE EXPLAINED BY EITHER DUNGEY-CYCLE MAGNETIC RECONNECTION OR KHI-RELATED MIXING DETAILED ANALYSIS IS REQUIRED TO BETTER UNDERSTAND AND DETANGLE THE RELATIVE IMPORTANCE BOTH PROCESSES PLAY IN SOLAR WIND ENTRY AT ROTATIONALLY-DOMINATED MAGNETOSPHERES. THE QUESTIONS TO BE ANSWERED BY THIS WORK WILL BE (1) WHAT THE OCCURRENCE RATE AND SPATIAL EXTENT OF KHI AND RECONNECTION OBSERVED AT THE MAGNETOPAUSE IS (2) THE RELATIVE CONTRIBUTIONS OF SOLAR WIND PLASMA ENTRY INTO THE MAGNETOSPHERE FROM KHI AND RECONNECTION AND (3) HOW THE KNOWN DAWN-DUSK DIFFERENCES IN KHI PROPAGATION AND OCCURRENCE AFFECT THE ACCESS AND ENERGIZATION OF SOLAR WINDORIGINATING IONS ALONG THE FLANKS. TO ANSWER THESE QUESTIONS WE PROPOSE TO USE DATA FROM CASSINI CAPS MIMI AND MAG TO FIRST CATEGORIZE AND ANALYZE ALL MAGNETOPAUSE CROSSINGS DURING THE SATURN CAMPAIGN AND THEN UTILIZE BOTH TEST-PARTICLE AND MAGNETOHYDRODYNAMIC (MHD) SIMULATIONS OF ION TRANSPORT AND ENERGIZATION ACROSS KHI VORTICES AS WELL AS RECONNECTION SITES. DETERMINATION OF PROXIMITY TO EITHER KHI OR RECONNECTIONS SITES WILL BE DONE USING MAGNETIC FIELD SIGNATURES (MAG) CHANGES IN PLASMA DATA (CAPS) AND ELECTRON SIGNATURES (MIMI/LEMMS). AFTER CATEGORIZING THE CROSSINGS WE WILL USE MIMI/CHEMS OBSERVATIONS TO STATISTICALLY STUDY THE CHANGE IN ABUNDANCE OF SOLAR WIND HE++ IONS ACROSS THE BOUNDARY TO DETERMINE THE EXTENT OF THE SOLAR WIND ION PENETRATION. THESE OBSERVATIONAL RESULTS WILL BE COMPARED TO BOTH TEST-PARTICLE AND MHD SIMULATIONS FOR CONTEXT. WE WILL THEN BE ABLE TO EXPLORE HOW THE EXTENT OF PLASMA ENTRY AND MIXING ACROSS THE BOUNDARY LAYERS DEPENDS ON THE DIFFERENT DYNAMIC PROCESSES AT THE MAGNETOPAUSE.